The invention relates to a motor vehicle comprising a safety device for protecting pedestrians or bicyclists colliding with the motor vehicle, wherein the safety device includes at lease one airbag, which is arranged on the vehicle body in such a way that in the non-activated basic state the airbag is folded up and in the activated unfolded state, at least partially covers a frame around the windshield.
DE 100 59 224 A1 discloses a safety device that is configured for a motor vehicle for protecting pedestrians and has an airbag. The airbag is disposed on the vehicle body in such a way that it is folded up in the non-activated state; and in the activated, unfolded state, the airbag covers a frame around the windshield. To this end, the airbag can be made in a shape that resembles a ring or a U, so that in the activated state the airbag always covers the “A” pillars of the motor vehicle.
In addition, the safety device known from the prior art has a windshield cover, which is stretched in front of the windshield by the airbag in the inflated state. Because of this windshield cover an advantageous energy absorption can occur to some extent in the central region of the windshield, so that any impact in this central region is less hard. The windshield cover can be made of a transparent material. If desired, an additional protective layer can be applied to the underside of the windshield cover.
The trend over the past years has been to strengthen the future maximum allowable acceleration values for an impact of the head of a pedestrian or bicyclist on the windshield. Numerous tests have shown that the rigidity of windshields can deviate widely, so that under some circumstances it is possible for individual windshields to exceed the future maximum allowable acceleration values upon a head impact.
The object of the present invention is to provide a motor vehicle with a safety device that guarantees—during a collision of the motor vehicle with a pedestrian or bicyclist—that the acceleration values of the head and, as a result, the potential head injuries, will be as low as possible upon impact of the head of the pedestrian or bicyclist on a windshield of the motor vehicle.
This and other engineering objects are achieved according to the invention with a motor vehicle comprising a safety device for protecting persons, such as pedestrians or bicyclists, that collide with the motor vehicle. The safety device comprises at least one airbag, which is arranged on the vehicle body in such a way that in the non-activated basic state the airbag is folded up and, in the activated (deployed) unfolded state, at least partially covers a frame around the windshield. In the activated, unfolded state the airbag spans a windshield cover in front of the windshield. The windshield cover has at least one region, in which a plurality of energy dissipators are distributed on the side of the windshield cover that faces the windshield. When a pedestrian or bicyclist hits his head on this region, the region is pressed against the windshield. At the same time, the energy dissipators cause prior damage to the windshield, so that the rigidity of the windshield in the region is reduced. As a result, the windshield gives way in a repeatable fashion when a head collides with this region. The head acceleration values are lower than in the case of a windshield that has not experienced prior damage.
In the activated, unfolded state the airbag covers a frame around the windshield. This frame-like shape is necessary in order to be able to stretch the windshield cover in front of the windshield. For this purpose, the airbag can surround circumferentially the entire windshield in the form of a ring. The airbag covers at least partially, or totally, in an advantageous manner the “A” pillars as the lateral boundary of the windshield and a bottom wind deflector as the lower boundary of the windshield. These are the regions of the motor vehicle that are especially unyielding. In order to cover these regions and to stretch the windshield cover, it is sufficient in a convenient way if the airbag is constructed in the shape of a U. The smaller the airbag, the less space it requires in the non-activated basic state, in which it is folded up; and, hence, the faster it can be inflated.
The windshield cover can consist preferably of a net or a foil. The foil is made ideally of a transparent material. In this way it is possible that the driver of the motor vehicle can still see the road lane through the transparent windshield cover with the activated airbag, even after a collision with a pedestrian or bicyclist and, if desired, can bring the motor vehicle to a standstill in a controlled manner. As an alternative, the windshield cover can also be made of the same woven fabric from which the cover of the airbag is made. In this case the central region has either a recess or a plurality of holes, through which the driver can still see the road lane at least to some extent.
The function of the energy dissipators, which are affixed to the windshield cover, is to cause prior damage to the windshield, when they are pressed against the windshield owing to the head crashing against the windshield cover. Energy dissipators that lend themselves especially well to this purpose are granular material. In this context, it is advantageous if each of the grains has at least one sharp corner and/or edge. When these corners and/or edges of the energy dissipators are pressed against the windshield, they can cause substantial damage to the windshield and, thus, intensify the desired effect.
Grains that have proven to be particularly suited are grains having a diameter between 0.5 mm and 2.5 mm. If the grains are too large, there is the risk that the impacting head will be injured on the grains; if the grains are too small, the windshield would experience too little prior damage under some circumstances. Suitable granular material includes both grains made of a natural occurring abrasive grain material, such as quartz, corundum or a lubricating gel, and grains made of a man-made abrasive grain material, such as a hard plastic or a metal. It is important that the grains exhibit adequate hardness in order to be able to cause considerable prior damage to the windshield. The windshield cover can also include a plurality of embedded wires. Then, the energy dissipators are formed by two intersecting wires.
The hard energy dissipators are conveniently embedded in a protective body made of a soft material. In this way it can be ensured that the windshield is not already damaged in the process of unfolding the airbag, but rather exclusively when a pedestrian or bicyclist actually crashes against the windshield cover. In this case the at least one energy dissipator is pressed through the respective protective body against the windshield and then causes prior damage to the windshield. As a result, the stretched windshield cover does not have to exhibit a minimum distance from the windshield in order to avoid damaging the windshield with the energy dissipators in the event that the airbag opens up unintentionally.
The energy dissipators are affixed in an advantageous way to the windshield cover at regular intervals to each other. In this way it can be guaranteed that the windshield cover is always pressed with the energy dissipators against the windshield independently of the exact location at which the head crashes against the windshield cover. In this case it has turned out to be particularly suitable to space the energy dissipators approximately 1 to 4 cm apart from each other.
According to an especially advantageous embodiment, the distribution of the energy dissipators is chosen in such a way that when the windshield cover is stretched, the regions of the windshield cover, which come to rest in front of the particularly rigid regions of the windshield, exhibit a very large number of energy dissipators. In this way it is possible that in the event of an impacting head of a pedestrian or bicyclist all of the regions of the windshield exhibit approximately the same acceleration values.
In most modern motor vehicles the windshield has a rigidity that is too high under some circumstances, especially in the peripheral regions. Therefore, a plurality of energy dissipators are affixed on the side of the windshield cover that faces the windshield in such a way that they are distributed preferably at least in the peripheral region of the windshield cover.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.